emilianobovetti/php-option

Lightweight option in PHP

v0.1.2 2018-02-19 09:13 UTC

Requires

• php: >=5.5.0

Requires (Dev)

• phpunit/phpunit: 5.*

GPL-3.0

• Emiliano Bovetti

• option

README

Tired of Trying to get property of non-object?

This is a porting of the option type in PHP.

Installation

composer require emilianobovetti/php-option

// import library
use EmilianoBovetti\PhpOption\Option;
// if you need direct access to Some class
use EmilianoBovetti\PhpOption\Some;

Creating Options

You can create options through constructors (e.g. new Some(0), new None) or using facade methods of the Option class.

Option::none() returns an instance of the None class. Since this class is stateless there is no need to create a new object every time that a None is needed.

Option::create($value, $empty = null) returns an Option object. By default it returns a None if the $value is null, or a new Some($value) otherwise.

You can change this behavior passing the $empty parameter. E.g. Option::create(0, 0) === Option::none()

If another option is passed to the create method, the option itself is returned.

If the $value is callable then the value that it yields is used.

If $empty is callable then it's applied to $value and a None is returned if it yields a falsy value.

Using Options

With a convenient syntax you can use PhpOption to get properties from objects and keys from arrays while handling nulls.

// $user object contains a reference to addres
// which contains a reference to city,
// but the user, the address and the city
// can be null
$city = isset($user->address->city) ? $user->address->city : 'Unknown';

// this line makes the same thing
$city = Option::create($user)->address->city->getOrElse('Unknown');

Options also offer a lot of flexibility.

// we can change this
if (isset($user->address->city)) {
    $city = $user->address->city;
    $result = $city === 'rome' ? 'home' : $city;
} else {
    $result = 'city unknown';
}

// with a little more compact solution
$result = Option::create($user)->address->city
    ->map(function ($city) { return $city === 'rome' ? 'home' : $city; })
    ->getOrElse('city unknown');

Wait, but I have an array!

// no problem, objects and arrays are treated identically
$user = [ 'defined' => [ 'key' => 0 ] ];

$key = Option::create($user)->defined->key->get(); // $key is 0

$user = null;

$key = Option::create($user)->undefined->key->getOrElse(0); // $key is 0 again

Okay, what if I have some resource intensive functions?

// use callbacks for lazy-evaluation
Option::create($user)->some->property
    ->orElse(function () { return $this->heavyLoad(); })
    ->orElse(function () { return $this->someFallback(); })
    ->getOrElse(function () { return $this->lastChance(); });

If $user->some->property exists and is not null, no methods get called. If the first callback gets called and returns a non-null value, the following functions aren't executed, and so on...

How to output Options?

echo Option::create($user)->address->city->name; // will print city name or empty string

Option methods

filter(Closure $function)

If the Option is a Some and the given $function returns false on its value, filter method returns None. Returns the Option itself otherwise.

map(Closure $function)

If the Option is a Some returns another Option wrapping the result of $function applied to Option's value. Returns a None otherwise.

each(Closure $function)

Applies given $function to the Option's value if is non-empty, does nothing otherwise. Returns Option itself.

get()

Gets the value of the Option or throws NoneValueException if the Option is a None.

getOrElse(mixed $default)

If the Option is a Some returns its value, returns $default otherwise.

$default can be:

1. a callback - which is called and its result returned if the Option is a None.
2. any other PHP value - which is returned in case the Option is a None.

getOrThrow(Exception $e)

Gets the value of the Option or throws $e if the Option is a None.

getOrCall(Closure $function)

If the Option is a Some returns its value, returns the value that yields $function otherwise.

orElse(mixed $default)

Acts like getOrElse, but returns an Option instead of its value.

isDefined() and isEmpty()

The first one returns true if the Option is not a None, the second one returns true if it is.

Dynamic methods

__toString()

A None gets casted to an empty string, while a non-empty Option returns the (string) cast of its value.

__get(string $name)

If the Option is a Some which contains an array or an object, it looks for the given key or property. If it exists and is not null, returns an Option wrapping this value. In any other case returns a None.

__isset(string $name)

Check if the given key or property exists in the Option's value.

E.g.

$array = [ 'defined' => [ 'key' => 0 ] ];
isset(Option::create($array)->defined->key); // true

isset(Option::create(null)->undefined->key); // false

__invoke(mixed $default)

Makes the Option callable. This is a shortcut for get() and getOrElse() methods.

E.g.

$option = Option::create(0);
$option(1); // 0
$option();  // 0

$option = Option::none();
$option(1); // 1
$option();  // NoneValueException

Like getOrElse method $default can be a callback or any other PHP value.

Run tests

git clone [e-mail]:emilianobovetti/php-option.git
cd php-option
composer install
./vendor/bin/phpunit